Lumps and bumps reveal Earth's varying gravity field

Emma Woollacott, 31st March 2011

The European Space Agency has released a model of the Earth showing how gravity varies across its surface.

Using data from the Goce satellite, the model, known as a geoid, shows areas with a similar gravitational pull in the same colors - the force is greatest in the raised yellow areas and weakest in the sunken blue ones.

Gravity varies across the globe because it isn't a perfect sphere and its mass is irregularly distributed. The image shows the surface of an ideal global ocean in the absence of tides and currents, shaped only by gravity.

The data should help scientists better understand a number of natural processes affected by gravity, including ocean circulation, sea level change, ice dynamics and earthquakes.

"GOCE will give us dynamic topography and circulation patterns of the oceans with unprecedented quality and resolution," says professor Reiner Rummel, former Head of the Institute for Astronomical and Physical Geodesy at the Technische Universität München.

"I am confident that these results will help improve our understanding of the dynamics of world oceans."

The Gravity field and steady-state Ocean Circulation Explorer mission was launched in 2009. ESA says that because of exceptionally low solar activity, it's been able to stay in low orbit and finish collecting data early, and there's enough fuel left to carry on making measurements until the end of next year.

"This is a highly significant step for the mission," says Rune Floberghagen, ESA's GOCE mission manager. "We now look forward to the coming months, when additional data will add to the accuracy of the GOCE geoid, further benefiting our data users."